1, Selection of the anti-corrosion schemeⅠ.Single tube stack anti-corrosion scheme(1), Anti corrosion of single tube stack with a residual life less
than 5 yearsUnder the circumstance that the reliability of the stack structure
meets the requirements, the original lining is not suggested to be
removed. Organic lining materials of rubber or hybrid polymer can
be adopted to conduct the anti-corrosion renovation.

(2), Anti corrosion of single tube stack with a residual life more
than 5 yearsOriginal lining is suggested to be dismantled and the principle of
the anti corrosion renovation is as below:

(2), The internal steel tube is not worthy of repair, then remove
the original tube and make a new one:A. Anti-corrosive lining for non-heat-supplying units of or below
300MW level should adopt the lightweight anti-corrosive brick
pasting scheme; hybrid Polymerization scheme can also be used.B. Anti-corrosive lining for heat-supplying units and units of
600MW level should adopt lightweight anti-corrosive brick masonry
scheme or hybrid polymerization scheme.

3, Anti-corrosive scheme for brick internal tube stack

(1). Under the premise that the internal tube is worthy of repair:A. Anti-corrosive lining for non-heat-supplying units of or below
300MW should choose lightweight anti-corrosive brick pasting scheme
preferentially.B. Anti-corrosive lining for heat-supplying units and units of
600MW level should adopt lightweight anti-corrosive brick masonry
scheme.

(2). The internal tube is not worthy of repair, then remove the
original tube and make a new one:A. Anti-corrosive lining for non-heat-supplying units of or below
300MW level should adopt the lightweight anti-corrosive brick
pasting scheme; hybrid Polymerization scheme can also be used.B. Anti-corrosive lining for heat-supplying units and units of
600MW level should adopt lightweight anti-corrosive brick masonry
scheme or hybrid polymerization scheme.4, Technical selection of the anti-corrosive scheme

Advantages and disadvantages of the anti-corrosive technology for
stacks

Anti-corrosive lining

advantages

disadvantages

Titanium plate or titanium steel composite plate

The passivation coating on the surface has excellent anti-corrosive
properties ；the service life is long；maintenance workload is small

expensive,hard to construct,hard to manage the quality of the weld
joint；long construction period of the renovation project

Glass fibre reinforced plastic(FRP)

High strength, high modulus；lightweight, insulating；anti-corrosive,
heat preserving；nice resistance to air, water, acid, alkali and
salt of ordinary concentration, various oil and solvents

Not appropriate for stack renovation because of the piecewise
integral forming; The disadvantage of FRP is that the basis
material of it has strict restrictions on the stack’s operating
temperature.

Imported foam glass brick

Small heat conductivity coefficient； non-hygroscopic, airtight,
resistant to acid and alkali；stable, easy to be processed and
nondeformable; short construction time.

The compressive strength and bending strength of glass brick is not
high. Crack and abrasion are easy to occur. Glue dosage has great
influence on the anti-corrosive lining of foam glass brick.
Inadequate glue quantity will cause contact between the acid liquid
and the tube directly through the cracks.

Domestic foam glass brickCeramic vitrified tiles

Short construction period；Low cost；Applicable to the renovation of power plant.

Glue dosage has great influence on the anti-corrosive lining of
foam glass brick. Inadequate glue quantity will cause contact
between the acid liquid and the tube directly through the cracks.In
the case that the construction control is not strict, there may be
defects, which is one of the problems of the veneer lining.

Glue dosage, treatment of the bottom and construction environment
conditions has important influence on the effect of the fiber
reinforced resin.The quality of fiber reinforced resin is hard to
manage.Flue gas temperature fluctuation occurs.Due to the lack of
thermal expansion coefficient of anti-corrosion materials and the
temperature stress between the fiber reinforced resin and the
matrix.,cracking and shedding of the anti-corrosive material will
be caused.

5, Technical selection of the anti-corrosive scheme

Technical parameters of the anti-corrosive materials for stacks

Anti-corrosive material

Compressive strength

Rupture strength

Linear thermal expansion coefficient

Water absorption per volume

Imported foam glass tiles

≥872KPa

Modulus lasticity12600kg/m²

≤5.5×10-6/℃

≤0.2%

Domestic foam glass tiles

≥1.2MPa

≥1.6MPa

≤6.0×10-6/℃

≤0.2%

Domestic Ceramic vitrified tiles

≥2.5MPa

≥1.4MPa

≤5.0×10-6/℃

≤0.5%

Fiber reinforced resin

Bonding strength>12MPa

Modulus lasticity still higher than 5.5GPa after thermal aging of
180℃